New Buck Institute study extends life span to human equivalent of 400 to 500 years

The Buck Institute sits nestled in the hills of Novato, California on Thursday, Mar. 28, 2013. Cellular Dynamics International is planning to rent lab space at the research facility. (IJ photo/Frankie Frost)
Frankie Frost

A new study by scientists at the Buck Institute for Research on Aging in Novato suggests that it may be possible to extend life span far longer than previously thought.

Experimenting with nematodes, the researchers combined two techniques that have previously demonstrated effectiveness in increasing the life span of a variety of organisms in the laboratory: yeast, nematodes, flies and rodents. The results, which are reported in the current online edition of "Cell Reports," surprised them.

The worms lived to the human equivalent of 400 to 500 years, about five times longer than the scientists had expected.

"When we got this result, it was kind of a shock," said Pankaj Kapahi, the lead scientist on the study and a Buck faculty member.

Kapahi said in addition to implications for human life extension, the study's results could also lead to new approaches for battling age-related diseases such as Alzheimer's and Parkinson's. Kapahi said the research suggests the possibility of employing combination therapies for aging in much the same way as is done for cancer and HIV.

One of the life extension techniques used in the experiment was the drug rapamycin, which is already licensed for use in humans.

"It was a well-known anti-cancer drug. Later on, it became clear it has life-extension effects," Kapahi said. "It also slows down a number of other age-related diseases."

Scientists discovered rapamycin's life-extension capability while searching for a drug that mimics the effects of caloric restriction, which had previously been identified as a means of extending life in laboratory studies.

The other technique employed in the new Buck study was to inhibit key molecules involved in insulin signaling. This is a technique that is already being used in humans to treat cancer and diabetes, Kapahi said.

The insulin-signaling approach typically doubles the life span of worms while rapamycin extends the life span of worms by 30 percent. Buck researchers had expected that using the two techniques simultaneously might result in an additive effect, an increase in life span of 130 percent.

"But in this case, they got these huge synergistic effects, which is really remarkable," said Malene Hansen, an associate professor at Sanford-Burnham Medical Research Institute in La Jolla, who is doing related research.

While scientists have found several ways of extending life in the laboratory, an understanding of how these effects are being produced has proved allusive.

"The whole organism enjoys the life-span extension," Hansen said, "but are there key tissues where the signals come from?"

Hansen said another important aspect of this new Buck study is that "they argue for an important role for the germline." In biology, germline refers to cells that pass genetic material on to an offspring, allowing the organism to reproduce.

In a prepared statement, the study's lead author, Di Chen, a former Buck postdoctoral fellow who is now an associate professor in China, said, "The germline was the key tissue for the synergistic gain in longevity."

Kapahi said in the past scientists have failed in identifying single genes responsible for long-lived humans. He said the new research suggests that may be because interactions between genes are playing a critical role in the longer life spans.

Kapahi said the next step will be to try to replicate the experiment using mice to determine if the synergistic effects extend into mammals.

Neither Kapahi nor Hansen are worried much about the potentially devastating effects on the environment that quadrupling the human life span would have.

"I don't study aging to find the Fountain of Youth or how to live forever," Hansen said. "That would raise a whole set of societal and ethical issues."

Hansen said her focus is finding therapies for age-related diseases, which account for "many if not most of the really serious diseases of our time."

Kapahi said the cost of each human life to society would be greatly reduced if people were able to avoid these age-related diseases.